1. Field of the Disclosure
The invention relates to inexsufflation of a subject during which peak expiratory flow rate is controlled.
2. Description of the Related Art
Coughing, also known as “airway clearance”, is a normal function of everyday life for most people. Inhaled air is drawn in slowly (<1 LPS). Then, the glottis closes and the expiratory muscles contract, increasing the subglottic pressure. To begin the cough, the glottis opens and the initial flow is the decompression of the air in the trachea. The lungs continue to empty at a rate of roughly 4 LPS until the lungs are sufficiently decompressed.
Some people, due to injury, disease, or even thoracic surgery, find it difficult to impossible to cough effectively on their own. For these people, assisted or artificial airway clearance is prescribed.
Artificial airway clearance can be achieved via many methods. One such method employs the use of a mechanical in-exsufflator (MI-E). A MI-E is a medical device that delivers positive airway pressure through the mouth, nose, or a tracheostomy gently filling the lungs to capacity (insufflation). It then very abruptly reverses pressure which generates an explosive expiratory flow, mimicking a cough (exsufflation).
In conventional systems, determining the initial (optimal) settings for a particular patient can be imprecise and/or inaccurate. Each patient has respiratory characteristics unique to them (e.g. airway resistance, lung compliance, patient effort, etc.), which can change over the course of the condition with which they are afflicted. Usually, through trial and error, and while relying on past experience, a physician arrives at settings that may or may not be optimal. Conventional systems may not provide confirmation that acceptable settings have been reached.